In the case of large parasols various fabric qualities can be used for manufacturing the parasol roof. This means that upon opening and closing the parasol the canopy fabrics stretch and warp in a different manner. Moreover, the dimensional stability and the stretching behavior of the fabric change over the lifetime. For a perfect fit of the canopy fabric it is advantageous if the position of the canopy strut ends can be adjusted individually.
Moreover, there are large parasols wherein the parasol roof is sewn together in such a manner that the seams are exposed to radiation, particularly to UV radiation, and therefore become permanently damaged. It is desirable if this can be avoided for the strained regions of the canopy strut ends.
In principle, welts are already known in the relevant technical field, e.g. from DE 84 30 086 U1 or CH 648 083 A5 for marquees, wherein a tension transverse to the welt shall be countered, or also for parasol roofs from WO 92/13470 A1, from CN 2894368 Y or CN 201393636 Y, wherein two fabric parts are joined together by means of the welts and wherein again a tension transverse to the welt is applied.